2 Origin of anal fin posterior, inserted nearer to caudal-fin base than to end of pelvic-fin base; tip of dorsal fin not reaching origin of adipose fin when depressed; pectoral fin not reaching origin of pelvic fin; pelvic fin not reaching or only reaching anus .......................................................................................................3

The morphology of the premaxillary tooth patches is considered to be a chief character for identifying genera in the tribe Glyptosternina (Chu 1979, 1981; Thomson & Page 2006), and as a character in elucidating the phylogeny of Glyptosternina (He 1995b, 1996). Dissection of the skeleton shows that the premaxillary tooth band of PareuchiloglanisZBK is separated into two patches (He 1996). We divide the premaxillary tooth band of PareuchiloglanisZBK into two types. In one type the premaxillary tooth patches appear separate, medially divided by a deeper indentation. This type is characteristic of P. kamengensis , P. feae , P. macropterusZBK and P. gongshanensisZBK . This group is distributed in and to the west of the Lancangjiang (Fig. 4) and overlaps that of OreoglanisZBK , PseudexostomaZBK and ExostomaZBK (Chu et al. 1990; Ng & Rainboth 2001; Ng 2004). In the other type, the premaxillary tooth patches appear to be joined with a shallow medial indentation. This type is characteristic of all other species of PareuchiloglanisZBK . This group is distributed in and to the east of the Lancangjiang(Thomson & Page 2006).

In the first group, the morphology of the premaxillary tooth patches is more similar to that of OreoglanisZBK species. These species of PareuchiloglanisZBK also have a sulcus between the maxillary barbel and the lower lip, and the lower lip is not connected to the base of the maxillary barbel. This characteristic is also similar to that of OreoglanisZBK species(Fig. 3). Based on morphology and geographic distribution, the authors consider P. kamengensis , P. feae , P. macropterusZBK and P. gongshanensisZBK to form a monophyletic group that may be a transitional group from PareuchiloglanisZBK to OreoglanisZBK . This group is distributed extensively in the Lancangjiang, Nujiang, Irrawaddy and Brahmaputra river systems, which implies that rivers in this area could have been historically connected with each other.